In the petroleum industry extensive use is made of moineau style pumps, so named after the french aviator who invented them. These pumps utilize metal rotors and polymer plastic rotors. The stator are secured with adhesive within a tubular stator housing. When a moineau style pump is new, there is a tight sealing engagement between the tubular stator housing and the stator. Upon rotation of the rotor, liquids are moved sequentially through a series of cavities formed between the tubular stator housing and the stator. After prolonged use the polymer plastic stator begins to wear and the rotor and stator are no longer able to move liquids efficiently due to inadequate sealing.
In order to service the moineau pump, the worn polymer plastic stator must be removed from the tubular stator housing and replaced with a new stator. At the present time the removal of the worn stator represents approximately one half of the cost of replacing the stator. Hydraulic or mechanical rams are used to break the bond of the adhesive and push the worn stator out of the stator housing. The tubular stator housing then must be reamed out to remove any residue of polymer plastic which remains.